Thromboembolism is a major complication of cancer therapy, particularly with newer agents, and is associated with increased mortality and morbidity in cancer patients. This problem involves disparate fields, and requires an interdisciplinary approach. The objective of this career development award is to provide the applicant, Dr. Alok Khorana, with the experience and knowledge necessary to become an independent clinical investigator in cancer-associated thrombosis. Dr. Khorana will accomplish this objective through the combination of a formal Master's program, directed reading, seminars and mentored research in a supportive institutional environment. A highly qualified and dedicated team of mentors with expertise in thrombosis, cancer and epidemiology, and with a history of training investigators, will supervise this plan and ensure that he achieves his goals. Dr. Khorana will examine risk factors related to the development of venous thromboembolism (VTE) during chemotherapy. The specific aims of this proposal are: 1) to develop and validate a risk model that will identify a group of cancer patients at high risk for development of VTE, 2) to prospectively identify the rate of asymptomatic and symptomatic VTE in a cohort of high-risk patients selected using this model, and 3) to prospectively identify markers of hemostatic and platelet activation that are associated with the development of VTE in this high-risk cohort. The first aim will be accomplished by conducting a secondary analysis of an ongoing prospective observational study, and the latter two aims through a prospective cohort study. Results from the proposed plan will have direct clinical significance by helping identify high-risk patients in a clinical setting. These data will also provide useful information for the design of future trials for prevention of thrombosis. Further, these studies will allow the applicant to enhance his expertise in risk assessment models, design and conduct of clinical trials, and studies of thrombosis. The proposed research plan and mentored career development activities will allow the applicant to develop into" an independent investigator conducting rigorous scientific research. Relevance: Cancer patients on chemotherapy can often develop blood clots, or thrombosis, which can be life-threatening or lead to complications. Thrombosis can be prevented using anticoagulant drugs, but this requires identifying which patients are most at risk. The proposed research plan will develop and test a risk" model to identify such patients, and then enroll high risk patients on a study to be screened during chemotherapy for thrombosis as well as test blood markers that may correlate with its development.